Carburetor



E. O. WIRTH EIAL CARBURETOR 24 a /Z 2z /4 f6 Original Filed Dec.

sept. 9, 1952 /3 /35 wwwZ 6 EL' Z Patented Sept. 9, 1952 UNITED STATES PATENT) OFFICE QRBURETOR Emil o;- Wirihfana Frederik Barred, south Bend; Ind., assignors `to Bendix Aviation Corporation; South Bend, 1 Ind., af corporation .of .Delaware Continuation of abandoned application Serial N o.

5153-126; December- 27 December; 18', 1948;. S

1i claims. (C1. 261-3'0 whiclrmay` `befbuilt at reasonable costand .which is: capable `fof accurately regulating thefuel supplyto maintain a. `properfuel-to-airratioithrough wide ranges oi?V engine load, speed, andvaria tions fin altitude such .as are1 experienced'with an aircraft engine.L

`Anotherobject fof: thefinvention islto eliminate boilinggofsthe `fuel :under high tempera-ture .or altitude conditions, such .as are experienced with an'aircraftengine, to thereby insure accurate.

metering. This-is accomplishedY by maintaining the fuel under positive. pressure until itis discharged intoltheair` .supply` to form combustible mixture for theiiengine.

Still` anotherobjectof .the invention is tonnely atomizeetheuel dischargedy into the airfs'tream toiproduce an ,improvedmixturecapable of Vbeing readily ignitedieven .though the engine is cold.

A ,further object ofthe .invention is to provide a fuel feeding ,device or system which willi-operate. properly in :any positioni sothatwhen installedon anaircraftrengine the latter will be properly. suppliedwith,fuelregardless of the position .of-,igh.t..

Itis' .a further `object ofthe invention to provid a .device or system of this character wherein fuel at constant pressureis supplied to avfuel' metering jet system andthence to a nozzle,A the metering: Ofthe fuel .being primarily controlled by controlling'thefuel pressure at the nozzle by a counterbalancing pressure and by suction'r'e# sulting from the `operation of the engine.

oz'lfueli feeding systemsy 1943.` This application erial No. 66,092

Further objects of therinvention relate-to modi?. cation of the fuelV control in accordance with@k variations ini the' pressure of air supplied .to theiengine; and to the provision ofan' Yeconomlzera-r-`H rangement including a variable` meteringz-jetf system to f vary the: richness. ofr tl'iemixture` for high power output operating conditions.`

Still further objects of the inventionlrelate to the inclusionof an idling system.- in a device 'ot this character forrsecuring-` accurate fuel meters ing-during operation atornear idlingbymeansi actuatedwith the throttle ffor varying .the eiecff tive capacity;v of the` variable metering, jet sys i tem;A and to the-'provision-bf anidle cut-ott for-1A stopping the flowof fuel when the engine fisftofr-l be stopped and `to .prevent discharge@ofrfuelfintof` the induction :passage at such times as theengineaf is inoperative.A l I i Y Otheri obj ects. and advantages` of the inventionh will be.` readilyapparent to those:si:il1ed4 iii-ther.` art from the following-1descriptionLtakenf-inacon--A nection with the :accompanying f drawing; which.

represents a preferred embodiment.; After confrsidering this embodiment skilled `persons-will.un:-` f derstand that manyy variations `maybe made- Without departing from the principlesdisclosed;` and` we contemplate the employment of. anyf structure; arrangements,- or modesfof operatione-l that are properly withinthe scope of the apV pended. claims. p

In the` drawings: Figure 1` diagrammatically illustrates` afuel feeding. system" embodyingthe present invention@ parts `of saidsystem beingshownin section;v

Figure -2 issan enlarged viewE of thefvariable metering unit..` i

there is-shown a main body member Iwv-hichl AA sti1lfurther'fobliect ofthe*` invention is to provdeadevice of this -characterwherein afiiid control valve isturged inopposite directions by respective means exerting substantially constant pressureswhichnornrally balance eachother and the control"of'saidvaive!ist effected by means adapted to" Vary the pressure of one ofthe `bal anceditpressure means"` A ifurther 1 object *of the` invention is fto provide a devicei-iotitthis-character# wherein on'elofl the balancezpressurezgmeans'is-ifunbalancedl according tdzindu'cti'orripassaget;suctionzwhiclr LIndy. be SUG" tinianterionfto: thes'fthrottlel-fvalve., i

contains nan induction passage l2 having an air` inlet I4 and an outlet I6, the airiinlet beingpro vided-with. an outer-surface |8-to whichanair thev manifold. If-` desired,` a'A supercharger may-bel used anterior to the body "member l0 -eitherrin1 kplace ofor in addition toa supercharger--posterior. to said bodyfmember; A1venturi20havingz sepa-vf'4 rable inlet and outlet sectionsis` positioned-in the.

induction passage. adjacent theA inlet- Illrfgtndeis-f formed with an annular. chamber: 22 whichgcorn.- n i municates with the interior. of thee4 venturi-l Referring more particularlytov the drawings,

through an annular slot 24 to be thereby subjected to Venturi depression. An annular chamber 26 is in free communication with the air entering the venturi through an annular opening 28, the opening 28 being preferably subjected to the impact pressure of the air supplied to the venturi. A throttle 30, lpivotally mounted on a throttle shaft 3 I, is disposed in the induction pas-v sage posterior to the venturi and is adapted to be manually actuated to control the air iiow to the engine.

Fuel is discharged into the induction passage I2 from a fuel discharge nozzle comprising a member 32 mounted in the wall of the bodyl i0 and extending transversely of the induction passage |2. The member 32 is provided with a re-l duced diameter end portion 34 which projects into an enlarged portion 38 of a tubular extension 40 of a valve guide and seat member 42. The nozzle is providedwith a fuel passage 44 andan air! passage 46, the latter being supplied by air from chamber V26 through a passage 48.

`iiow from the nozzle control unit 60 to the discharge nozzle. The valve' 68 is urged to the right in the closing direction by a spring 10 varranged to be variably loadedby anA adjustment screw 12. The stem of valve 68 `is of triangular cross sectionor otherwise relieved to'per'mit fuel flow therepast and, is slidable'` within the nozzle bar 42. f In this arrangement the valve is not fixed to the diaphragmy 66 but is maintained in abutting relation therewithby a light spring 14, thus eliminating any tendency forrthe valve to bind in its valve guide and seat memberf16 as a result of misalignment between the diaphragm and the guide member.Y The chamber 64 of the fuel nozzle unit l60 is connected Vto `the Venturi aniilulus 22 by a passage 18 having a calibrated rentrlction 80 therein and the chamber 62 issup.- rilied with fuel by a connection 82 leading from ny iiuel metering unitindicated generally at 90 which in turn is supplied with fuel through a conduit 92 connected with a chamber 94 in a lateral extension 95 of the body I0 and chamber M is provided with an inlet passage 96 adapted to be connected byl a pipe 98 with an engine driven fuel pump 99 of any wellknown type which delivers fuel at a substantially constant superatmospheric pressure.

The fuel meteringunit 00,*anterior to the nozzle control unit 66, which determines the effective area of the fuel metering restriction under Y various conditions of operation, may be formed Y as a part of the'main bodyl I 0 or may be a separable unit secured to the body or other convenient support. A metering unit similar tothe one described herein is disclosed in our Patent No.

2,445,846 issued July 27, 1948. ,In lthe present unit, a diaphragm |I0 separates the interior of the unit into chambers |f|2 and ||4, chamber ||2 being connected with the conduit 82 which leads to the chamber 62 of the nozzle control unit 60,

While chamber |I4 is connected to the Venturi annulus 22 by a conduit 26 and passages |28 orifice |20 formed in the plug ||8, said valve ||6 normally being at least slightly open.

The metering unit includes a casing memvber |24 enclosing a chamber |25 within which is a tubular sleeve |26' which is slidable on a guide pin |21. The sleeve |26 provides a oneway connection between diaphragm ||0, and a cross bar |28 secured to a rod |29 urged to the left, as shown inthe drawing, by a spring |30 and slidable in a guide |3I. The rod |29 is provided with a nut |32 adjacent its free end, said nut being engageable by a nger |34' secured to the throttle shaft 3|. A spring retainer |35, slidable on an enlarged portion |36 of sleeve |26', is yieldingly urged to the right against a wall |31, by a preloaded spring |38 reacting between said retainer |35 and a second spring retainer |39 abutting against shoulder |40 of casing |24, said retainer |39 havin-g an 'opening through which sleeve |26' is adapted to freely move.v The l I0, through an opening |44 in wall |31 and engage saidV retainer |135. Further movement of the sleeve to the left is then yieldingly resisted by the spring |38. The movement of the rod |29 and cross bar |28 tothe left is limited by i stop |53 integral with the casing member |24` at such times as the throttle is open beyond its idling or near idling positions andthe diaphragm is urged to the left by the pressure of fuel in chamber |I2. The sleeve |26 limits such movement of the diaphragm and when the throttle is opened beyond the near idling position'the fuel pressure in chamber ||2 and suction in chamber ||4 move the diaphragm ||0 and valve ||6 to the left only sufliciently far to withdraw the valve partially from the orifice |20. During `high power operation, however, ythe fuel presvvalve II6 is completely Withdrawn from the orifice |20 against the pressure of spring |38.

Thus during idling, the valve ||6 enters part way into and cooperates with the orifice |20 to limit the area for fuel fio'w. As the throttle is Aopened from the idling range the valve I I6 moves to the left until the flange |42 engages the spring retainer |35, thereby increasing the eifective fuel metering area to permit a sufficient amount of fuel flow for normal cruising operation. At high power output the valve ||6 is moved to the left, as shown in the drawings, against the force of spring |38 which is to be compressed so that at a predetermined high Venturi suction said valve is completely Withdrawn from the orifice |20, whereby an enriched mixture is produced as is desired during high power operation.

An automatic mixture control unit, indicated generally at |60, may, if desired, be provided to modify the suction in chamber 64 in accordance with barometric pressure and/or temperature. This unit includes a bellows |10 adapted to actuate a valve member |16v which cooperates with a valve seat 200 to'control communication between a conduit |86, connected With chamber 26 through a conduit |90, and a conduit |98 inchamber H2 and the suctionin chamber H4; This reduction of fuel supplied Vto the engine is eected by means of the Vmechanical linkage between the throttle valve and thefuel valve H6. Under other operating conditions the fuel-toair ratio may be automatically modied by the metering jet system 90. As the effective area of this jet system determines the quantity of fuel which will be supplied to the nozzle control unit 6 0 for any given suction in passage 18, increasing or decreasing the said effective area of the metering jet |20 as said suction correspondingly varies, the' richness of the mixture will be correspondingly increased or decreased. Various types of metering jet systems may, of course, be used with devices of the instant character to automatically vary the richness of the mixture to produce a rich mixture during high power operation, or to produce a leaner mixture during light load operation, orto otherwise vary the richness of the mixture under particular conditions of operation ofthe engine. l

Under some circumstances it is also desirable to manually `vary the richness of the fuel mixture and in the present device such control may be effected by the valve 254, said mixture being enriched by closing said valve 254 for high speed and power conditions of the engine and leaned when' said valve is opened, for economical operation of the engine. l

When it is desired to stop the engine the fuel cut-off valve 2|@ is closed and said valve is maintained closed whenever the engine is not running, as above pointed out. l

It will be apparent from Ithe foregoing that a relatively simple, inexpensive pressure type carburetor has been provided that is capable of accurate fuel-to-air proportioning under various operating conditions, it being thought that the invention andmany of its attendant advantages will be understood from the foregoing description though said invention has been illustrated in connection with but a single modication thereof, and it will be appar-ent that various changesmay be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefor'e described being merely a preferred embodiment.

We claim: Y 1. In a fuel supply system for an internal combustion engine having an induction passage and a throttle thereinr an engine driven fuel pump adaptedto deliver fuel at a substantially constant pressure; a fuel conduit connecting the pump with .the induction passage; a Variable metering jet system in said conduit; a valve for said conduit posterior to said jet; means including av diaphragm subjected to fuel pressure on one side and so constructed and arranged that the valve is urged in the Yopening direction by said fuel pressure, the opposite side of said diaphragm being subjected to air pressure; means including a spring urging the valve in theclosing direction With a force normally balancing the fuel pressure on the diaphragm when the air pressure on the diaphragm is substantially atmospheric andthe Valve is partially open; means adapted to act on the diaphragm to reduce the effective force of the `spring upon increase of air flow throughv the induction passage anterior tothe throttle; means connected with the throttle and adapted to Lvary the metering jet capacity; manually controlled means adapted to vary the effect of the air flow upon the diaphragm; and

8 meanssoconstructed and arranged as to at least in part control the variable metering jet system by suction in the induction passage anterior to thethrottle.

2. In a fuel supply system for an internal combustion engine having an induction passage andA a throttle therein: an enginedriven fuel pump adapted to deliver fuel at a substantially constant pressure; a fuel conduit connecting the pump with the induction passage; a valve for said conduit; means, including a diaphragm, so constructed and arranged that the valve is urged in the opening direction in accordance with the pressure of fuel on said diaphragm; means including a spring and a chamber for air under pressure varying with variations in air flow through the induction passage for urging the valve in the closing direction with a force normally balancing the fuel pressurer acting to urge the valve in the opening direction; and a variable metering jet system anterior to said valve and comprising a casing, a diaphragm separating said casing into a fuel chamber and an air chamber, a metering jet, a movable valvemember connected with the diaphragm vand adapted to control the effective capacity of the metering jet,

a guide fixed to the casing, a sleeve slidable on4 the guideV and having one end adapted to be operably connected with the diaphragm, a spring retainer adjacent one end of the sleeve and held against movement in one direction relative to the casing, a second spring retainer slidably disposed relative to the sleeve, a preloaded spring reacting between said spring retainers, an abutment on the sleeve adapted to engage the second mentioned spring retainer, said spring retainer being so positioned as to permit limited free movement of the sleeve, therst mentioned spring retainer having an opening therein through which the sleeve is` adapted to pass, and: means adapted to operably connect the sleeve with the throttle valve for positively moving the movable valve member to a partly closed position when the throttle valve is in the idling position.

3. In a fuel supply 'system for an internal combustion engine having an induction passage controlled by a'throttle and an engine driven fuel pump adapted to deliverfuel at a substantially constant'pressure: a variable metering jet system comprising a casing; a diaphragm separating said casing into a fuel chamber and an air chamber; a metering jet; a movable valve member connected with the diaphragm and adapted Ato control the effective capacity of the metering jet; a guide fixed to the casing; a sleeve slidable on the guide and having one end adapted to be operably connected with the diaphragm; a first spring retainer adjacent one end of the sleeve and held against movement in one direction relative to the casing; a second spring retainer slidably disposed relative to the sleeve; a preloaded springV reacting between said spring retainers; an abutment on the sleeve adapted to engage the second mentioned spring retainer, said springV retainers being so positioned as to permit free movement of the sleeve, the first spring retainer having an opening therein through which the sleeve is adapted to pass; and means adapted to operably connect Vthe sleeve with the throttle valve for positively moving the movable Valve member to partly closed position when the throttle valve is in the idling position.

4. A three-stage metering jet assembly for use in a fuel system for an engine having a throttle comprising a fuel passage, a metering orifice in said passage, a valve for said orifice, a linkage between said valve and said throttle for positively limiting the degree to which said valve will open while said throttle is in closed or nearly closed position, a means responsive to fuel pressure for urging the valve in the opening direction, rand a yieldable stop means adapted to main- .tainsaid valve in a fixed partially open position throughout the engine cruising range and to permit the said valve to move in the opening direction for high power output.

5. A three-stage metering jet assembly for use in a fuel system for an engine having a main control element comprising a fuel passage, a metering orifice in said passage, a valve for said orice, a linkage between said valve and said element for limiting the degree to which said valve will open while said element is regulating the engine for low power output, a means responsive to fuel pressure for urging the valve in the opening direction, and a yieldable stop means adapted to maintain said valve in a fixed partially open position throughout the engine cruising range and to be moved by the pressure responsive means in the direction to permit said valve to open further.

6. A three-stage metering jet assembly for use in a fuel system for an engine having an induction passage with a throttle comprising a fuel passage, a metering orice in said passage, a valve for said orifice, a linkage between said valve and said throttle for positively limiting the degree to which said valve will open while'said throttle is in closed or nearly closed position, a means responsive to unmetered fuel pressure and Venturi suction for urging the valve in the open ing direction, and a yieldable stop means adapted to `maintain said valve in a iixed partially open position throughout the engine cruising range and to permit said valve to move in the' opening direction for high power output.

`'LA three-stage metering jet assmbly for use in a fuel system for an engine having a throttle comprising a fuel passage, a metering orifice in said passage, a valve for said orifice, alinkage between said valve and a control means for said throttle for positively limiting the degree to which said valve will open While said throttle is in closed or nearly closed position for engine idling, av means responsive to unmetered fuel pressure for urging the valve in the opening direction, and a yieldable stop means adapted to maintain said valve in a fixed partially open position in opposition to the pressure responsive means throughout the engine cruising range and to be moved by the pressure responsive means in the direction to permit said valve to open further for high power output.

8. In a charge forming device for an internal combustion engine having an induction passage with a throttle valve therein, a fuel conduit, an orifice in said conduit, a pressure responsive valve for regulating the effective size of said orice, said valve adapted to be urged in the opening direction by fuel pressure, yieidable stop means for maintaining said valve in a fixed position throughout the engine cruising range, said stop means being adapted to yield when the fuel pressure reaches a predetermined value to provide an enriched fuel-air mixture for irish power output, and a linkage actuated by the throttle valve for positively limiting the degree to which said valve will open during engine idling.

9. In a fuel metering system for aninternal combustion engine having an induction passage with a throttle and a venturi therein, a fuel conduit adapted to deliver fuel from a source to said induction passage, a metering orifice in said conduit, a valve for regulating the eifective size of said orifice, a pressure responsive means for controlling said valve, said means being urged in the valve opening direction by fuel pressure and Venturi suction, a linkage actuated in conjunction with the throttle for positively limiting the degree to which said valve will open during engine idlng, and a spring loaded stop means for retaining said valve in a xed partially open position throughout the engine cruising range, sad stop means being adapted to yield when the fuel pressure and Venturi suction reach predetermined relative values to provide an enriched fuel-air mixture for high power output.

10. A fuel flow regulating means in a fuel system for an engine having an induction passage With a throttle therein, comprising a conduit, an orifice in said conduit, a valve for regulating the effective size of said orice, a throttle actuated means for positively limiting the degree to which said valve will open for engine idling, a means responsive to fuel pressure for urging said valve in the opening direction, yand a resilient stop means for retaining said valve in said orifice at a fixed position of greater effective orice area than at idling throughout the engine cruising range, said stop means being adapted to yield in the valve opening direction when the fuel pressure reaches a predetermined value to provide an enriched fuel-air mixture for high power output.

11. A ,fuel iiow reguating means in aiuel system for an engine having an induction passage with a throttle and venturi therein, comprising a conduit, an orice in said conduit, a valve for regulating the effective size of said orifice, a throttle actuated means for positively limiting the degree to which said valve will open for engine idling, a means responsive to fuel pressure and Venturi suction for urging said valve in the opening direction, and a spring loaded stop means for retaining said valve in said oriiice at a fixed position of greater effectve orifice area than at idling throughout the engine cruising range. said stop means being adapted to yield in the valve ,opening direction when the fuel pressure and Nenturi suction reach predetermined relative values to provide an enriched fuel-air mixture for high power output.

.EMIL O. WIRTI-I. FREDERIK BARFOD.

REFERENCES CITED The following references are of record. in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,796,734 Tice ..-1 Mar. 17, 1931 2,283,021 Udale May 21, 1942 2,445,846 Barfod et al. July 27, 194'8 2,447,264 Beardsley Aug. 17, 1948 2,457,765 Winkler Dec. 28, 1948 

